Marina Artuso 1

Beyond the Standard Model:

the clue from charmMarina Artuso,

Syracuse UniversityDoDo, DoK-+

K-

K+

+

K-

K+

Marina Artuso 2

Experimental strategies considered

Mixing Comparison between hadronic and lepton tagged modes

from C=1 DoDo pairs Study of “right-sign” leptons versus “wrong sign

leptons” CP violation

Direct CP violation in Do and D+

Indirect CP violation in Do decays CP violation measurements exploiting the quantum

coherence of the DoDo pair Rare and forbidden decays Decay constants revisited

Marina Artuso 3

A glimpse into the world of new physics?

Mixing CP violation } Exploit quantum

coherence of initial state at the and D0D0

Study interference effects induced by strong phases (Dalitz plot analyses)

Marina Artuso 4

Experimental Situation (May/2001)

D0D0 mixing

Marina Artuso 5

D0D0K+K+& rD

•No rDCSD component because of quantum statistics

•Sensitivity can be enhanced by adding other modes (such as K(*)

+l(*)l).

•Standard Model predictions quite uncertain. We will not span the full range of Standard Model predictions, but we may see “new physics driven”, possibly distinguishing x from y

2

22 yxrD

UL(sqrt(rD))0.01 @95%CL

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A COMPREHENSIVE MAPPING

OF MIXING PARAMETERS - 1

Final state (C=-1) (C=+1)K-+K-+ A4(x2+y2)/2 4A4(r2+ry’+3/8(x2+y2)

K-+K+- A4(1-2r2cos2-1/2(x2-y2))

A4(1+2r2cos2-+4ry-3/2(x2-y2))

K-+S A2AScos A2AS

y

Comparison of CPeven and odd allows determination of cos

Linear in y

hep-ph/0103110Gronau, Grossman & Rosner

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CP eigenstates

CP(+1) eigenstates

Channel B.F.(x103) 3fb-1 #(3fb-1 D0D0)

K-K+ 4.1 110,000 9,400

1.6 36,000 3,000

15.0 54,200 4,600

CP(-1) eigenstates

s 3.5 61,600 5,300

s 6.0 98,400 8,400

s 10.6 176,000 15,000

s 10.0 141,000 12,000

s 4.3 39,100 3,300

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Phase determination from C=-1 sample

2 cosS

SCS

SD D

S

A r

•We sum over all the CP eigenstates of a given sign to

obtain =(K-+S+)

•We can use MM technique to increase statistics

•Expected accuracy in cos is 0.05

S

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Lepton tagged samples

Final state (C=-1) (C=+1)

K-+l - A2A2(1-1/2(x2-y2)) A2 A2 (1+2ry-3/2(x2-y2))

K-+ l + A2 A2 (r2-1/2(x2+y2)) A2 A2 (1+2ry+3/2(x2+y2))

Sl + A2 ASy2 A2 A S

y+3y2)

l-

l+

l-

l+

~

l+

l+

CP even – CP odd asymmetries linear in y

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CP Violation experimental search

techniques Direct CP violation in D decays CP violation in the decay of a Do Do pair CP violation in final state distributions

(DVV) Order of magnitude expected in Standard

Model 10-3

New physics can enhance CP asymmetries + in this scenario they can emerge in Cabibbo allowed modes

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CP violation in charm decays

Present experimental data: FOCUS Acp(D+K-K++)=-0.0010.0220.015, FOCUS result Acp(K+K-)=-0.0010.022 0.015

CLEO Acp(D0K-K+)=+0.050.02180.0084

CLEO-C error 0.01 with 3 fb-1 with a variety of techniques. In some measurements b-factories are very competitive

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CP asymmetries from flavor tagged decays

)]KK)(ek[(N)]KK)(ek[(N

)]KK)(ek[(N)]KK)(ek[(Na cp

•Necessary ingredients:

•Flavor tag (lepton/kaon)

•CP eigenstate

•Obtain acp, for example:

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Acp with flavor tagged CP eigenstates

CP eigenstate

Flavor tagged sample

A

K+K- 10,200 0.01

Ks0 10,400 0.01

Ks 3,500 0.02

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Acp sensitivities

Self tagging modes (D+, Ds)

O(10-3)0.009D++K*0

O(10-3)0.007D++O(10-3)0.008D++

SM predictions

Acp(Lint=3 fb-1)Mode

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DoDo f+ f+ or f- f-(f+=K+K-,+-,Ks

•A single background free event CP violation

CP eigenstate 1 CP eigenstate 2 # for 100% CPV

K+K- K+K- 174

K+K- Ks0 171

K+K- 00 183

Ks0 Ks0 136

•We can increase statistics x3-4 using MM technique discussed before

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CP violation studies in the Dalitz Plot

High statistics background free DalitzPlot analyses may turn out to be the most sensitive probes of CP violation in D decays

Not only “Beyond SM”, also QCD etc..

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Rare and forbidden decays

Some D decays are forbidden: Standard Model expectations are several order of magnitude below any experimental reach laboratory for “Standard Model background free” searches for new physics

the charm threshold region has the advantage of high efficiency and low background both for charged particle final states and final states including and o.

Sensitivities to branching fractions (10-6) expected

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Leptonic Decays: D l

+ Introduction: Pseudoscalar decay constants

Q and q can annihilate

probability is to wave function overlap

Example -:

22+ 2 2 2

221

(P ) 1 | |8 F P P Q

Pq

mG m M Vf

M

In general for all pseudoscalars:

_

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fD and new physics

22

2

22

2

( )

( )1

1s

s

s

s

D

DB D

D

m

m

mm

mm

B

We can probe violation of universality

222

2ta( ) 1 1 nsD s

s l SM

H cm

m mB D l B

m

Effect can be a few % with new physics

2HDM prediction

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Summary on decay constant reach

Decay mode

Decay constant

½

B/B½

Vcq/Vcq

fDq/fDq

D+ fD 1.9% 0.6% 1.1% 2.3%

Ds fDs1.4% 1.0% 0.1% 1.7%

Ds fDs1.2% 1.0% 0.1% 1.6%

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Conclusions

CLEO-c can probe for physics beyond the Standard model with 4 different strategies Mixing studies CP violation studies Rare decays Precision decay constant measurements

Phenomenology is very rich, some measurements unique (quantum coherence of initial state)

Search for signatures of physics beyond the Standard Model in charm is very important and our studies will be complemented by other experiments (BaBar, BELLE, BTeV…)